The present invention relates to a non-impact printing method for recording graphic symbols on ordinary paper by means of selective emission of ink particles by an ejector.
Methods and devices are known wherein drops of liquid ink are emitted selectively through a nozzle by an ejector device actuated through the medium of a piezoelectric crystal and wherein each electrical stress applied to the crystal produces a corresponding compression of the volume of the chamber containing the ink and a corresponding emission of drops through the nozzle.
It is also known to produce the emission of drops by applying a potential difference between conductive liquid ink and the mouth of a nozzle, as in U.S. Pat. No. 1,958,406.
One of the problems which arise with the aforesaid devices and methods known in the art is that the liquid ink encrusts the nozzle and ends by blocking it in the course of time. The choice of special water-based inks does not completely solve the problem of encrustation.